US2671840A - Electric switch - Google Patents

Description

March 9, 1954 H. c. swAY 2,671,840

` ELECTRIC SWITCH Filed March 26, 1952 FLC/2 'InQentor Henry C. Swag,

His Attorjneg.

Patented Mar. 9, 1954 ELECTRIC SWITCH Henry C. Sway, Bridgeport, Conn., assignor to General Electric Company, a corporation oi' New York Application March 26, 1952, Serial No. 278,657

Claims.

This invention relates to electric switches, more particularly to such switches having a pair of coacting contact elements, and its principal object is to provide such a switch wherein failure of the contacts to close due to an accumulation of foreign matter on the surfaces of the contacts, as dust or an oxide of the material of which the contacts are made, is substantially eliminated.

More specifically, this invention has for an object the provision of an improved electric switch embodying improved contact structure and means for effecting a sliding or wiping motion between the contacts as they open and close so as to eiect a cleaning action and thereby prevent the accumulation of foreign matter between them.

In accordance with my invention, I provide an elastic arm which carries one of the switch contacts. This contact is mounted on a portion of the arm which is bowed with respect to the main body of the arm, as by angularly relating that portion to the main body, and it engages a xed contact whose contact area is substantially parallel to the angled portion of the arm; and the bias of the arm holds the contacts in engagement. An actuating element engages the body of the arm to move it to effect separation of the contacts and to permit it to move to reclose them. But its motion to open the contacts is resisted by a second elastic member which engages the arm substantially at the juncture point between the main body of the arm and its angularly deflected contact carryingportion; and also is arranged to bias the contacts closed. And its tension is such that the switch arm when operated to open, rst warps about the second elastic member as a fulcrum before the contacts open, thereby to wipe or slide its contact across the face of the other contact, and only after this happens does the second elastic member yield to permit the contacts to open. Moreover, the parts are so arranged that the contact pressure is actually increased by the action of the second or pressure applying elastic member during the wiping stage of the opening operation. Likewise when the contacts close, they close with a wiping action.

My invention will be better understood from the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

In the drawing, Fig. l is a plan view of an electric switch embodying this invention; Fig. 2 is a vertical sectional view taken through the line 2 2 of Fig. 1 and looking in the direction of the arrows; Fig. 3 is a fragmentary sectional View similar to Fig. 2 illustrating the switch in its closed position and drawn to a larger scale than Figs. l and 2; Fig. 4 is a sectional View similar to Fig. 3 but illustrating the switch elements at one stage of the opening operation; and Fig. 5 is a (Cl. 20D-164) View similar to Figs. 3 and 4 but illustrating the switch contacts in their open position.

Referring to the drawing, this invention has been shown in one form as applied to an electric switch comprising a base I formed as a flat plate having parallel upper and lower flat surfaces; this plate may be formed of any suitable electrically insulating material such as a suitable electrically insulating plastic. Mounted upon the plate I is a fixed contact 2 formed of any suitable material such as silver, and in the shape of a rivet, and mounted in rivet-like fashion upon a supporting bracket 3; the bracket 3 is of angular shape, as shown, having a base portion il and an upwardly extending contact supporting section 5 arranged at an angle to the base 4 so that it supports the contact 2 with its engaging face at an angle of substantially 45 to the top surface of the base I. The base t has one end portion, the lower end portion, as viewed in Fig. 1 wrapped around that edge of the base I, and its other end 6 constitutes a terminal connection for the xed contact 2; the wrapped portion of base :l is inserted in a recess 5a provided in the edge of plate I so that it is secured against turning with respect to the plate. The bracket 3 as a whole is riveted to the base I by means of a rivet 1, and this rivet 1 also forms the terminal connection for an electrical supply conductor 8 which it will be understood will be connected in a suitable electrical circuit to be controlled.

Also mounted upon the base I to coact with the xed contact 2 is a movable contact 9 similar to the contact 2. The contact 9, however, is mounted upon an elastic switch arm II] which by its inherent resiliency tends to maintain the two contacts in closed position, as shown in Figs. 2 and. 3. The contact arm I0 is in the form of a relatively elongated strip extending lengthwise across the top of the base I from the contacts toward the left of the plate, as shown, where its left-hand end is anchored to the base I through the medium of a suitable terminal plate II; as shown, the left-hand end of the switch arm 1s connected to the terminal plate II by means of a suitable rivet I2; the arm II) is prevented from rotating with respect to the terminal plate II by means of a tongue I3 formed on and extending upwardly from the terminal plate and received in a slot I4 provided for it in the end of the contact arm. Here again the terminal plate may be connected to a suitable external conductor I5 by means of a suitable rivet I6 which rivet also functions to secure the terminal plate II to the base I and thereby also serves to connect the switch arm I0 to the base I. This terminal plate like the terminal plate 6 also has one end, its lower end as viewed in Fig. 1, wrapped around the lower edge of the plate in a recess-I1 provided for in the plate so as to pre.

by said contact, means anchoring the other end of said arm so that it biases said contacts together with a predetermined force, biasing means applying an elastic force to said arm substantially at the juncture of said body and end portions to increase the pressure between said contacts, and an operating element for applying a force to said arm intermediate its said other end and said juncture to open said contacts, said biasing means applying an elastic force of such magnitude that initially it resists movement of said arm away from said xed contact whereby said arm flexes to effect relative shifting movement and increased pressure between said contacts prior to their opening and thereafter yields to permit opening movement of said arm.

2. Switch structure comprising a base, a fixed contact on said base having a contact area in a plane at an acute angle to said base, an elastic switch arm lying over said base having an end remote from said contact fixed to said base and its other end portion adjacent said contact, said latter end portion being deected outwardly from the body of said arm to lie in a plane substantially parallel to said rst plane and having a contact area engageable with said xed contact area, the resiliency of said arm biasing said contacts together, a second elastic arm relatively unyielding as compared with the flrst having one end remote from said contact secured to said base and its other end engaging said first arm at the juncture thereof with its deiiected contact end portion and biasing said arm to increase said contact pressure, and an actuating member engageable with said rst arm at a point intermediate its fixed end and said juncture to move it away from and to permit it to return toward said base thereby to open and reclose said contacts, said second elastic arm applying an elastic force of such magnitude that initially it resists movement of said rst arm away from said fixed contact whereby said first arm exes to effect relative shifting movement and increased pressure between said contacts prior to their opening and thereafter yields to permit opening movement of said first arm.

3. Switch mechanism comprising a flat base, a fixed contact on said base having a contact area lying in a plane substantially 45 with said base, an elastic switch arm having one end fixed to said base extending from said end across said base toward said xed contact where its other end deflects outwardly from the base at an angle of substantially 45, said latter end carrying a contact area biased into engagement with said fixed contact area by said elastic switch arm, a second elastic arm relatively unyielding as compared with the rst having one end remote from said contacts secured to said base and its other end engaging said first arm at the juncture thereof with its deflected contact end portion and biasing said first arm to increase said contact pressure, and an actuating member engageable with said first arm at a point intermediate its fixed end and said juncture to move it away from and to permit it to return toward said base thereby to open and reclose said contact areas, said second elastic arm applying an elastic force of such magnitude that initially it resists movement of said first arm away from said fixed contact area whereby said first arm exes to effect relative shifting movement and increased pressure between said contact areas prior to their opening and thereafter yields to permit opening movement of said flrst arm.

4. Switch structure comprising a base having a flat supporting surface, a fixed contact member on said surface having a contact area lying in a plane forming an acute angle with said surface, a pair of superimposed elastic arms on said base attached together and to said surface at one end, the outer arm being relatively more rigid than the inner arm and both biased toward said surface, and the outer arm curving outwardly away from the inner arm from their xed ends to a point adjacent the other end portion of the inner arm where it curves inwardly to engage said inner arm, said other end portion of said inner arm deflecting outwardly at the point of engagement between said arms at an acute angle with respect to said surface, which angle is substantially the same as said first mentioned acute angle, a contact on said deflected end engageable with said fixed contact area, and an actuating member engageable with said inner arm intermediate its fixed end and said point of engagement to operate it to effect the opening and closing of said contacts, said outer arm applying an elastic force of such magnitude that initially it resists movement of said inner arm away from said xed Contact whereby said other end portion pivots about said point of engagement to effect relative shifting movement and increased pressure between said contacts prior to their opening and thereafter yields to permit opening movement of said inner arm.

Switch structure comprising a base having a plane supporting surface, a xed contact arm on said surface having a contact area lying in a plane substantially 45 to said surface, an elastic switch arm relatively long as compared with its width extending lengthwise along said surface and having one end adjacent said fixed contact area deected outwardly at an angle to the body portion of said arm so as to be substantially parallel to said xed contact area and having a contact area engageable with said xed area, means anchoring the other end of said arm to said surface to iiex said arm to bias said contact areas together with a predetermined force, a second elastic arm relatively more rigid than the rst substantially coextensive with the body portion of the flrst and spaced therefrom substantially throughout its length but having one end engaging said first arm at the juncture between the body thereof and its deflected end portion, thereby to act as a fulcrum for said first arm, means anchoring the other end of said second arm to said base to cause it to engage said juncture with a predetermined force, and an actuator engageable with said flrst arm at a point intermediate said juncture and its said other end to effect the opening and closing of said contacts, said second elastic arm applying a force of such magnitude that initially it resists movement of said rst arm away from said fixed contact whereby said deflected end portion pivots about said juncture to effect relative shifting movement and increased pressure between said contacts prior to their opening and thereafter yields to permit opening movement of said flrst an HENRY C. SWAY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,804,748 Derrick May 12, 1931 2,199,357 Dillman et al. Apr. 30, 1940 2,507,381 Morse May 9, 1950

Images